Plot a range of values of a NDVI calculated in Google Earth Engine

Question

I just perform a NDVI classification, and I want to know if I can plot or display the values of the NDVI lower than 0.8, or within a range for example from 0.3 to 0.5 and the rest of values in black or just not to plot them.

Here is part of my code:

//cargar coleccion de landsat
///////////////////////////////////////////////////////////////
var l8 = ee.ImageCollection('LANDSAT/LC08/C01/T1_TOA')


//geometry with the AOI 
var roi = geometry;

//filtrar la imagen de acuerdo a la cobertura de nubes en el poligono
////////////////////////////////////////////////////////////////////
var l8f = l8.filterBounds(roi);

var withCloudiness = l8f.map(function(img_zone) {
  var cloud = ee.Algorithms.Landsat.simpleCloudScore(img_zone).select('cloud');
  var cloudiness = cloud.reduceRegion({
    reducer: 'mean', 
    geometry: roi, 
    scale: 30,
  });
  return img_zone.set(cloudiness);
});

var filteredCollection = withCloudiness.filter(ee.Filter.lt('cloud', 10));


var image = ee.Image(filteredCollection.filterBounds(roi)
    .filterDate('2017-03-30', '2017-07-30')
    .sort('CLOUD_COVER')
    .first());



var red = image.select('B4');

//infrarrojo cercano
var NIR = image.select('B5')


var nvdi = (NIR.subtract(red)).divide(NIR.add(red)).rename('NDVI');


Map.addLayer(nvdi,{min: -1, max: 1},'ndvi_rice_1')

Answer 1

Not sure if this is the most direct way or not, but ee.Image has built-in filtering methods (less than [lt], greater than [gt], etc.). They return a boolean which you can multiply against your original image:

var nvdi = (NIR.subtract(red)).divide(NIR.add(red)).rename('NDVI');
var filtered = nvdi.gt(0.75); // boolean (0,1) where nvdi > 0.75
var multiplied = nvdi.multiply(filtered); // multiply to set <= 0.75 to 0
Map.addLayer(multiplied,{min: -1, max: 1},'ndvi_rice_1'); // plot

Answer 2

You can simply use .and()

For example

var nvdi = (NIR.subtract(red)).divide(NIR.add(red)).rename('NDVI');

var filtered = nvdi.lt(0.75).and(nvdi.gt(0.35));  // to get between say 0.35 and 0.75 

Map.addLayer(filtered,{min: -1, max: 1},'ndvi_rice_1'); // plot`